1. Technical Field
The present invention describes condensation products of polyether-modified and optionally hydrophobically modified monoesters and/or -amides of .alpha.,.beta.-unsaturated dicarboxylic acids and ammonia, their preparation and use.
2. Prior Art
Polyamino acid derivatives, in particular polyaspartic acid, have recently attracted particular attention because of their properties, in particular their biodegradability and their similarity to naturally occurring structures. Proposed applications are inter alia as biodegradable complexing agents, water softeners and detergent builders. Polyaspartic acid is generally obtained by alkaline hydrolysis of the direct synthesis precursor polysuccinimide (PSI, anhydropolyaspartic acid), the cyclic imide of polyaspartic acid. PSI can be prepared, for example, in accordance with EP 0 578 449 A, WO 92/14753, EP 0 659 875 A or DE 44 20 642 A from aspartic acid, or is obtainable, for example according to DE 36 26 672 A, EP 0 612 784 A, DE 43 00 020 A or U.S. Pat. No. 5, 219, 952 A, from maleic acid derivatives and ammonia. Proposed applications for these customary polyaspartic acids are inter alia as encrustation inhibitors, builders in detergents, fertilizer additive and auxiliary in tanning.
DE 4327494, EP 0578449 and EP 0578450 describe the preparation of polysuccinimide from aspartic acid or maleic acid derivatives in polyethylene glycols as solvents. Here, there is no incorporation of the polyether into the product.
The reaction of polysuccinimide with amines, which has been described by various working groups, leads to polyaspartic amides (Kovacs et al., J. Med. Chem. 1967, 10, 904-7; Neuse, Angew. Makromol. Chem. 1991, 192, 35-50). The ring opening of polysuccinimide using polyamines and the subsequent alkaline hydrolysis for the preparation of polyaspartic acid derivatives for applications as superabsorbers is described, for example, in WO 95/35337. DE 19525365 describes the modification of polysuccinimide with amines and amino-functional polyethers for the preparation of paper auxiliaries.
Kataoka et al. describe, in Macromol. Chem. Phys. 1995, 196, 1899-1905, poly-L-aspartic benzyl ester with terminally linked polyether block for pharmaceutical uses. The preparation of these enantiomerically pure products, however, proceeds via the N-carboxy anhydrides of L-aspartic acid and is very complex and uneconomical.
For applications inter alia as emulsifier, dispersant and surfactant, copolymeric polyaspartic esters partially esterified with long-chain fatty alcohols or their derivatives are of particular interest. Such compounds are readily obtainable on the basis of maleic monoesters and ammonia, as explained in DE 195 45 678 A or EP 96 118 806.7 A.
A disadvantage in the property profile of such polyaspartic acid derivatives having carboxylate side chains as hydrophilic component is, however, the pH dependency of the behavior. Changes in the pH cause undesired changes in the hydrophilicity, e.g. as a result of protonation of carboxylate groups, which is noticeably a disadvantage in their application properties, e.g. as regards the pH, thermal and long-term stability of the preparations, for example in the field of cosmetic W/O and O/W emulsions.
The object of the present invention is therefore to provide copolymeric polyaspartic acid derivatives having improved application properties which also contain nonionic hydrophilic groups.